Skip to main content
U.S. flag

An official website of the United States government

Geochemical investigation of the hydrothermal system on Akutan Island, Alaska, July 2012

January 9, 2014

We have studied the geochemistry of the hot springs on Akutan Island in detail for the first time since the early 1980s. Springs in four discrete groups (A-D) along Hot Springs Creek showed generally higher temperatures and substantially higher Na, Ca, and Cl concentrations than previously reported, and total hot-spring discharge has also increased markedly. The springs now account for a heat output of ~29 MW, about an order of magnitude more than in 1981. Gas samples from the hot springs and from a fumarolic area on the flank of Akutan Volcano show high 3He/4He ratios (>6.4 RA) after correction for air contamination and reveal a common magmatic heat source. Hot-spring gases are unusually rich in N2, Ar, and CH4, suggesting that the water has boiled and lost CO2 during upflow beneath the flank fumarole field. Gas geothermometry calculations applied to the flank fumarole field implies temperatures of 200–240 °C for the reservoir, and Na-K-Ca geothermometry implies temperatures near 180 °C for the outflow waters that feed the hot springs. The results of our study confirm the existence of a substantial geothermal resource on the island.

Publication Year 2014
Title Geochemical investigation of the hydrothermal system on Akutan Island, Alaska, July 2012
DOI 10.3133/sir20135231
Authors D. Bergfeld, Jennifer L. Lewicki, William C. Evans, Andrew G. Hunt, Kinga Revesz, Mark Huebner
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Scientific Investigations Report
Series Number 2013-5231
Index ID sir20135231
Record Source USGS Publications Warehouse
USGS Organization Volcano Hazards Program; Volcano Science Center-Menlo Park